1. Field of the Invention
The present invention relates to zoom lenses and image pickup apparatuses including the zoom lenses, and more particularly, to a zoom lens suitable for use in a still camera, a video camera, a digital still camera, a surveillance camera, etc., and an image pickup apparatus including the zoom lens.
2. Description of the Related Art
Recently, digital still cameras and digital video cameras including a solid-state image pickup element, such as a CCD and a CMOS device, have been commonly used. The number of pixels included in the solid-state image pickup element has been increased and, accordingly, small, high-magnification optical systems having high optical performance have come into widespread use.
For example, U.S. Pat. No. 7,177,092 discusses a wide-field-angle zoom lens having a high zoom ratio (about 10) from a wide-angle range to a telephoto range.
In addition, Japanese Patent Laid-Open No. 2007-47538 discusses a small zoom lens having a high zoom ratio (about 10) from a wide-angle range to a telephoto range.
In the zoom lens according to U.S. Pat. No. 7,177,092, the field angle 2ω at the wide angle end is 76° and the zoom ratio is about 10. Thus, a large field angle and a high zoom ratio are obtained. However, the overall lens length at the telephoto end is relatively large.
According to Japanese Patent Laid-Open No. 2007-47538, a small zoom lens with a high zoom ratio of about 10 is provided. However, a large image-plane variation occurs in a meridional cross section during zooming from the wide-angle end to the telephoto end.